1. Field of the Invention
The present invention relates to a broadband wireless communication system. More particularly, the present invention relates to an apparatus and a method for supporting hybrid automatic repeat request for anonymously allocated bandwidth in a broadband wireless communication system.
2. Description of the Related Art
As wireless communication system technology advances, a legacy system and a new system coexist in some cases. In this case, capability between the legacy system and the new system is in question. For example, an Institute of Electrical and Electronics Engineers (IEEE) 802.16e system, which is one type of IEEE 802.16 system, still exists, and improvement of the legacy 16e system performance is under way.
As an example of a method to enhance the performance of the 16e system, Hybrid Automatic Repeat reQuest (HARQ) is applied to uplink management messages. When HARQ is applied to the uplink management messages, the coverage can be extended and thus the system can support users in a wider area. While a current standard of the 16e system partially supports HARQ, HARQ is not supported for RaNGing-REQuest (RNG-REQ) and Bandwidth Request Header (BRH) transmitted after a terminal transmits a ranging code.
When the terminal is not allocated resources from a base station, the terminal transmits a certain ranging code to request the resource allocation. Terminals arbitrarily select their ranging code. Because the terminals may select the same ranging code by chance, collision may take place. Hence, after a certain time, a certain ranging code is selected and transmitted again. The base station successfully receiving the certain ranging code cannot identify which terminal transmits the ranging code. Instead of general resource allocation information, the base station allocates the resource using a MAP Information Element (IE) called Code Division Multiple Access (CDMA)_Allocation_IE. A general resource allocation MAP includes an IDentifier (ID) representing the terminal to receive the MAP, the amount of allocated resources, and the allocation location. By contrast, the CDMA_Allocation_IE identifies the terminal with an index of the received ranging code and a frame number of the location of the received ranging code, and includes the resource amount allocated to the identified terminal and the allocation location information.
Since the HARQ applied to the resource allocated with the CDMA_Allocation_IE is not supported currently, the CDMA_Allocation_IE does not include the HARQ related information. However, when a format of the CDMA_Allocation_IE is changed to apply the HARQ to the resource allocated with the CDMA_Allocation_IE, the capability with the existing terminals is lost.